I am considering why not use a simpler approach?
For example, writing down 15 words on papers, and storing the remaining 9 words on an encrypted USB drives and online emails. Certainly, both the paper documents and electronic file should be kept with multiple copies.
-snip-
Question: Given the first 15 words out of 24, can a hacker crack the wallet?
Go for the simpler method, but why not 12 words out of 24?
mnemonic with 9 missing words is quite safe, but 12 is safer.
It can also provide you potential deniability if you can generate valid first 12 words or 12 last words when used stand-alone.
Creating a 24-word seed phrase with one half part valid has a good chance but getting both two parts as separate valid seed phrase may be low.
You may need a script to generate the latter. (
can anyone provide the numbers if the latter if possible?)
For safety/deniability, fund each part with low amount so even if one got hacked, the attacker may think that it's the actual contents of the compromised seed phrase so he wont be looking at your emails or flash drives for the other part.
On the other hand, Attackers will likely think that it has another part hidden if the seed phrase is only 15-words or invalid.